Siberia Jurassic discovery of new ORNITHOPOD with feathery structure and scales-Dinosaur sculpture

GODEFROIT, Pascal, Institut Royal des Sciences Naturelles de Belgique, Brussels,
Belgium; SINITSA, Sofia, Institute of Natural Resources, Ecology and Cryology, SB
RAS, Chita, Russia; DHOUAILLY, Danielle, Université Joseph Fournier, La Tronche,
France; BOLOTSKY, Yuri, Institute of Geology and Nature Management, FEB RAS,
Blagoveschensk, Russia; SIZOV, Alexander, Institute of the Earth’s Crust, SB RAS,
Irkutsk, Russia
Recent discoveries in Middle–Late Jurassic and Early Cretaceous deposits from
northeastern China have revealed that numerous theropod dinosaurs were covered by
feathers. Furthermore, filamentous integumentary structures were also recently described
in rare Early Cretaceous ornithischian dinosaurs from Liaoning Province in China.
Whether these filaments can be regarded as epidermal and therefore part of the
evolutionary lineage towards feathers remains controversial. Here we describe a new
basal neornithischian dinosaur, based on isolated bones and partial skeletons collected in
two monospecific bonebeds from the Middle–Late Jurassic Kulinda locality in the
Transbaikal region (Russia). Varied integumentary structures were found directly
associated with skeletal elements, supporting the hypothesis that simple filamentous
feathers, as well as compound feather-like structures comparable to those in theropods,
were widespread amongst the whole dinosaur clade. Moreover, scales along the distal
tibia and on the foot closely resemble the secondarily-appearing pedal scales in extant
birds. More surprisingly, dorso-ventral movements of the tail were prevented by large
imbricated scales on its dorsal surface. It is hypothesized that, at the same time early
feathers evolved within the whole dinosaur clade, genetic mechanisms limiting the
growth of long epidermal structures on the distal portion of the hind limb and on the tail
were selected as they facilitate bipedal terrestrial locomotion.